Colloidal silicon nanoparticles synthesized by picosecond laser ablation

Abstract

Silicon nanoparticles suspended in deionized water were obtained by the laser ablation of solids in liquids technique. A silicon wafer target was ablated with a Nd:YVO4 pico-second laser emitting at 1064 nm with 10 ps pulse width at a repetition rate of 402 kHz with an energy per pulse of 106 µJ. The effect of fluence changes in nanoparticle size and optical properties was studied. The fluence was varied from 2 to 6 J/cm2 by attenuating the beam by means of optical attenuators. Results show a strong relation between nanoparticles size and fluence values. Optical characterization gives bad gap values higher than that of bulk Si, indicating the existence of quantum confinement effects produced by size reduction of Si nanocrystals.